# JSON Key Denylist

> JSON Key Denylist is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Validates a JSON object by identifying and filtering top-level keys that appear in a caller-supplied denylist, returning counts and normalized findings.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/json-key-denylist
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/json-key-denylist-8a549c99
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_l046y4DQXK8EG5ut-3OH3

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability json-key-denylist-8a549c99 -d '<json body>'
```

Example prompt: Before sending this plan object to the downstream tool, check it against my denylist of forbidden keys — ['password', 'secret', 'token', 'internal_id'] — and tell me which ones, if any, are present and how many violations were found.

## When to prefer this

Use this endpoint when an agent needs a lightweight, in-memory, stateless key-denylist check on a JSON object before passing it to a downstream tool with a stricter contract, and when no external provider or persistent storage should be involved. Prefer this over custom validation logic when you need a versioned, deterministic result with counts and normalized output for auditability.

## Known failure modes

- Denylist array exceeds 256 items — request rejected
- Input object exceeds 128 top-level properties — request rejected
- Individual denylist string exceeds 8192 characters — request rejected
- Malformed JSON body — parse error returned
- Payment not attached or insufficient USDC — 402 response

## How this service works

JSON Key Denylist: JSON Key Denylist finds top-level object keys present in an explicit denylist from bounded caller-supplied values without an external provider. Call JSON Key Denylist before an agent hands structured data or a batch plan to a downstream tool with a stricter contract. Returns the bounded transformation or validation finding with counts, normalized values, and a versioned result contract for JSON Key Denylist as versioned deterministic JSON. Price: $0.001 USDC via x402 on Base.…

## Output

A versioned deterministic JSON response containing: the count of denied keys found, the list of matched (denied) keys, normalized values, and a versioned result contract indicating which keys from the input object matched the supplied denylist.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "denied": {
   "type": "array",
   "items": {
    "type": "string",
    "maxLength": 8192
   },
   "maxItems": 256,
   "description": "Denied supplied to JSON Key Denylist; used only for this bounded calculation and processed in memory without retention."
  },
  "object": {
   "type": "object",
   "description": "Object supplied to JSON Key Denylist; used only for this bounded calculation and processed in memory without retention.",
   "maxProperties": 128,
   "additionalProperties": true
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "passed": false,
   "denied_keys": [
    "password"
   ]
  },
  "schema": "delx/util-json-key-denylist/v1",
  "status": "advisory",
  "evidence": {
   "retained": false,
   "input_sha256": "e2140fb14617296830e26895419ba5db41e0d9b605a101ae52d4dc0f016e86e2",
   "external_calls": 0
  },
  "operation": "data_batch:json_key_denylist"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/json-key-denylist-8a549c99/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.delx.ai](https://www.zero.xyz/host/api.delx.ai/llms.txt)